The aim of the experiment is to determine the input resistance of a transistor connected in
common emitter mode.
+Vcc 3,!
(a) Connect the circuit as shown in Figure 1.
(b) Ask the Supervisor to check the circuit connection.
(c) Copy Table 1 into your answer booklet.
Table 1
la(~) |
Va(V) |
|
.. |
10 |
|
20 |
|
35 |
|
40 |
|
50 |
|
70 |
|
(d) Switch on the power supplies.
(e) Set Vcc to give Vc of 3 V.
(f) Adjust VaB to give ls of 10 ~A.
(e) Set Vcc to give Vc of 3 V.
(f) Adjust Ves to give Ie of 10 IlA.
(g) Measure and record the value of Va (V) in Table 1.
(h) Repeat steps (f) and (g) for other values of ls in Table 1.
(i) Switch off the power supplies.
(j) Plot a graph of la on the vertical axis against Va on the horizontal axis.
(k) From the graph drawn in 0), deduce the input resistance.
The expected answers were:
Table 1
'a(J,.lA) |
Va(V) |
10 |
0.746 |
20 |
0.778 |
35 |
0.810 |
40 |
0.818 |
50 |
0.834 |
70 |
0.859 |
